Iris information acquisition apparatus and iris identification apparatus

ABSTRACT

An iris recognition system capable of remarkably reducing time taking from an image pickup of an iris image to generation of an iris code and of simplifying the construction is implemented. A sensor  10  comprises a group of pixels arranged in polar coordinates. An iris image is controlled so that the iris image is correctly formed on the sensor  10 , particularly, the center of the iris image matches. The inner and outer diameters of the iris are detected according to the iris image formed on the sensor  10,  and the difference between the inner diameter and the outer diameter in the radial direction is detected. The number i of pixels of each ring in the case of division into the predetermined number of concentric ring bands is calculated according to the difference. A weighted mean processing part  13  performs a weighted mean operation according to the number i of pixels. A band-pass filter  15  performs a processing in the tangential and radial directions of feature extraction of the iris image of each ring band and generates the iris code with a binary format formed by a binary circuit  16.

FIELD OF THE INVENTION

This invention relates generally to an iris information acquisitionapparatus, an iris identification apparatus and the others, andparticularly to techniques capable of remarkably reducing time from animage pickup of an iris image to generation of an iris code, and capableof simplifying the iris information acquisition apparatus, the irisidentification apparatus and the like.

BACKGROUND OF THE INVENTION

Security systems accompanying development of high computerization inrecent years require high reliability and convenience. In these securitysystems, for example, key, password, ID card, IC card, signature,voiceprints, fingerprints, biometric features (face pattern, set ofteeth, retina, iris pattern and so on) are used as recognition means.Generally, in order of description of the above recognition means,degree of problems that these recognition means must be carried, areforgotten, are difficult to operate, are lost, are forged, etc.decreases, with the result that the recognition means have highreliability while the security systems become complicated and expensive.

The fingerprints among the above recognition means have been adopted bythe police etc. of the whole world in the past and have been the mostfamiliar personal identification means. However, a pattern of thefingerprints at the time of registration is not identical with that ofthe fingerprints at the time of matching since the fingertips are soft,and also, a false acceptance rate which is a probability of deciding thepatterns identical in spite of the different patterns of thefingerprints and a false rejection rate which is a probability ofdeciding the patterns different in spite of the identical patterns ofthe fingerprints are said to become about 10 to 20% since thefingerprints themselves are easy to transform.

Also, in a system for matching a blood vessel pattern on the retina, todetect this blood vessel pattern, behavior of looking through a devicefor detecting the blood vessel pattern is forced and the false rejectionrate becomes high due to influence of retinitis (hemorrhage of fundusoculi, white patch, exudation) and so on.

On the contrary, the iris pattern which has a demerit of hiding the irisin an eyelid is said to be almost immutable until death since two yearsof age, and a personal identification rate using the iris pattern hashigh reliability and thus, the iris pattern is said to be the mostexcellent personal identification system. As shown in FIG. 15, the irismeans a region 101 having a pattern drawn radially on the outside of apupil 100.

The personal identification system using such the iris pattern isdisclosed in U.S. Pat. No. 5,291,560, for example. Also, an “IrisIdent”(registered trademark) system made of SENSAR Inc. in the U.S.A. is usedas a practical system. As shown in FIG. 16, this system roughlycomprises two illumination parts 110, a camera part 111, a processingpart 112, and cables 113 for connecting the camera part 111 to theprocessing part 112. And then, the processing part 112 is connected to ahost computer (not shown). A personal recognition processing using thesystem is generally performed according to the following procedure.

First, a three-dimensional position of the eye of human locating at thefront of the camera part 111 is calculated on the basis of stereoscopicvision by two wide-angle cameras in the camera part 111. Thiscalculation is performed by the processing part 112 on the basis ofimage pickup information fed from the wide-angle cameras.

Secondly, a zoom camera in the camera part 111 is focused on thethree-dimensional position fed from the processing part 112 and zoommagnification is inversely proportioned to the distance.

Thirdly, by this, an iris image caught by the zoom camera is taken witha CCD image sensor of said zoom camera and is fed to the processing part112.

Fourthly, the processing part 112 divides an iris portion (a region fromthe inner boundary to the outer boundary of the iris) in the taken irisimage into eight concentric bands so as not to be influenced byvariations in the pupil diameter. This is because the inside of the irisportion stretches and contracts in response to change in the pupil andthus the iris pattern itself stretches and shrinks. But, the outside ofthe iris portion does not change.

Fifthly, a convolution operation using a two-dimensional Gabor filterfor feature extraction is performed every the divided band and aband-pass filtering is performed and the result is formed in binarycode.

Sixthly, an iris code of 256 bits is calculated from the obtained binaryinformation every the band.

Lastly, The processing part 112 performs personal identification bydeciding whether the calculated iris code is matched with the previouslyregistered iris code or not. This personal identification may beperformed through the host computer (not shown) connected to theprocessing part 112.

In the personal identification system using the iris pattern mentionedabove, however, the normal CCD image sensor arranged in a grid shape isused when the iris image is acquired, so that a coordinate of the irisportion of the iris image taken by the CCD image sensor must betransformed from an orthogonal coordinate system to a polar coordinatesystem and further, the convolution operation to each the transformedband must be performed. Since it takes an enormous time to process thecoordinate transformation or the convolution operation, the is personalidentification system had a problem that such the coordinatetransformation or the convolution operation greatly affects a delay inprocessing time of the whole identification processing.

Although the above problem may be solved by enhancing the calculationcapability of the processing part 112, a new problem has arisen in thatthe enhancement of the calculation capability requires a high costnaturally, and obstructs miniaturization and weight-saving of thepersonal identification system including the processing part 112.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an irisrecognition and identification method and its system capable of removingthe above-mentioned problems of the prior art.

It is another object of the present invention to provide an irisrecognition and identification method and its system capable ofremarkably reducing time required from image: pickup of an iris image togeneration of an iris code as well as of simplifying the system.

It is yet another object of the present invention to provide an irisrecognition and identification method and its system capable ofremarkably reducing time required from image pickup of an iris image togeneration of an iris code and further capable of simplifying thesystem.

According to an aspect of the present invention, there is provided aniris information sensor comprising an image pickup sensor having a groupof photoelectric conversion pixels arranged in polar coordinates,wherein image light from an iris region of an eye is focused on theimage pickup sensor so that the center of an iris image formed on thesensor substantially matches with the pole of the polar coordinates ofthe sensor and the photoelectric conversion pixels of the sensor aresequentially scanned to read out an iris image signal.

The image pickup sensor may be made of a group of pixels arranged inconcentric circles.

The image pickup sensor may also be made of a group of pixels arrangedin a spiral shape extending in the radial direction.

According to another aspect of the present invention, there is providedan iris information acquisition apparatus for obtaining imageinformation of an iris region, comprising:

an image pickup sensor having a group of photoelectric conversion pixelsarranged in polar coordinates;

image pickup optical system means for focusing image light from the irisregion on the image pickup sensor;

optical axis operation control means for matching the center of an irisimage formed on the sensor with the pole of the polar coordinates of thesensor;

region determination means for determining the iris region by acquiringthe inner and outer diameters of the iris according to an iris imagesignal obtained by the sensor; and

read scan means for scanning the determined iris region in apredetermined sequence and obtaining an output value corresponding toinformation of the iris region.

The read scan means for scanning the determined iris region may scan thedetermined iris region at least in the tangential direction.

The read scan means for scanning the determined iris region may scan thedetermined iris region in the tangential and radial directions everygiven width.

The read scan means may divide the determined iris region intopredetermined concentric ring bands and determine the number of pixelsof the radial direction of each ring band, and also read the outputvalue corresponding to information of each ring band in which weightedmean is performed according to the number of pixels.

The region determination means may determine the iris region accordingto amplitude of a feature extraction signal, said feature extractionsignal obtained by passing the image signal through a band-pass filter,said image signal obtained by scanning the image pickup sensor in thetangential direction.

The said region determination means may determine the iris regionaccording to level variation in the image signal obtained by the scan inthe radial direction of the image pickup sensor.

The optical axis operation control means may calculate the direction andsize of an error between the center of the iris image formed on theimage pickup sensor and the pole of the polar coordinates of the sensorto control a matching of the center of the iris image with the pole ofthe polar coordinates of the sensor, by further passing the featureextraction signal through a low-pass filter, said feature extractionsignal obtained by passing the image signal through the band-passfilter, said image signal obtained by scanning the image pickup sensorin the tangential direction.

The iris information acquisition apparatus may further comprisesillumination means for irradiating illumination light to the eye and agroup of light receiving elements for receiving reflected light from theeye of the illumination light, the optical axis operation control meanscontrolling a matching of the center of the iris image with the pole ofthe polar coordinates of the image pickup sensor according to an amountof receiving light of the group of light receiving elements.

According to still another aspect of the present invention, there isprovided an iris information acquisition apparatus for obtaining imageinformation of an iris region of an eye, comprising:

an image pickup sensor having a group of photoelectric conversion pixelsarranged in polar coordinates;

image pickup optical system means for focusing image light from the irisregion on the image pickup sensor;

illumination means for irradiating illumination light to the eye havingthe iris;

optical axis operation control means for matching the center of an irisimage formed on the sensor with the pole of the polar coordinates of thesensor;

light adjustment control means for definitely controlling the innerdiameter of the iris image formed on the sensor by irradiating visiblelight to the eye having the iris from the illumination means andadjusting an amount of the light and defining the pupil diameter; and

read scan means for scanning the sensor in a predetermined sequence andreading image information of the iris region.

The image pickup optical system means may include a zoom lens anddefinitely keeps the outer diameter of the iris image formed on theimage pickup sensor by the zoom lens.

The pixel of the image pickup sensor each may have a light receivingregion with an approximately rhombic shape having each diagonal in theradial and tangential directions of the polar coordinates.

The pixel of the image pickup sensor each may also be arranged in aregion with an approximately rhombic shape surrounded by the lightreceiving regions with the approximately rhombic shape.

The iris information acquisition apparatus may further comprise iriscode generation means for generating an iris code according to theoutput value read by the read scan means.

The iris code generation means may comprise comparison means forcomparing a band-pass filter receiving the output value and output ofthe band-pass filter with a predetermined threshold value.

The iris code generation means may generate the iris code by comparingthe output value of a plurality of continuous pixels with output of atarget pixel.

It is possible to add information on the effective range of the irisregion to the iris code.

It is also possible to add information on resolution of the image pickupsensor to the iris code.

It is further possible to add information on tilt of the eye to the iriscode.

It is further possible to add information on whether the iris code isthe right eye or the left eye to the iris code.

The iris information acquisition apparatus may further comprises a groupof light receiving elements for receiving reflected light from the eyeof light irradiated by said illumination means, said optical axisoperation control means controlling a matching of the center of the irisimage with the pole of the polar coordinates of the image pickup sensoraccording to an amount of receiving light of the group of lightreceiving elements.

The optical axis operation control means may calculate the direction andsize of an error between the center of the iris image formed on theimage pickup sensor and the pole of the polar coordinates of the sensorto control a matching of the center of the iris image with the pole ofthe polar coordinates of the sensor, by further passing the featureextraction signal through a low-pass filter, said feature extractionsignal obtained by passing the image signal through the band-passfilter, said image signal obtained by scanning the image pickup sensorin the tangential direction.

The optical axis operation control means may control a matching of thecenter of the iris image formed on the image pickup sensor by moving amirror placed in an optical path between the eye of the iris of asubject and the sensor with the pole of the polar coordinates of thesensor.

The optical axis operation control means may control a matching of thecenter of the iris image formed on the image pickup sensor by moving thesensor with the pole of the polar coordinates of the sensor.

The optical axis operation control means may control a matching of thecenter of the iris image formed on the image pickup sensor by a verticalangle variable prism placed in an optical path between the eye of theiris of a subject and the sensor with the pole of the polar coordinatesof the sensor.

The optical axis operation control means may control a matching of thecenter of the iris image formed on the image pickup sensor by mutuallytranslating a plurality of lenses placed in an optical path between theeye of the iris of a subject and the sensor with the pole of the polarcoordinates of the sensor.

The image pickup sensor may comprise a linear sensor in which pixels arearranged in the radial direction and rotation driving means forsynchronously rotating the linear sensor around the pole of the polarcoordinates, and a function equivalent to the group of the pixels of thepolar coordinates may be achieved by the rotation of the linear sensorthrough the rotation driving means.

The pixel constructing the image pickup sensor each may be made of a MOSsensor or a CCD sensor.

The pixel constructing the image pickup sensor each may be made of adevice for detecting edge information electrically or optically.

The pixel density in the radial direction of each pixel of the imagepickup sensor may correspond to the rate of stretching and shrinking ofthe iris.

The image pickup sensor may be made of a group of pixels arranged in aspiral shape extending in the radial direction.

According to still another aspect of the present invention, there isprovided an iris identification apparatus for acquiring an iris coderepresenting information of an iris region of an eye and comparing andmatching the acquired iris code with a previously registered iris code,comprising:

an image pickup sensor having a group of photoelectric conversion pixelsarranged in polar coordinates;

image pickup optical system means for focusing image light from the irisregion on the image pickup sensor; optical axis operation control meansfor matching the center of an iris image formed on the sensor with thepole of the polar coordinates of the sensor;

region determination means for determining the iris region by acquiringthe inner and outer diameters of the iris according to an iris imagesignal obtained by the sensor;

read scan means for dividing the determined iris region intopredetermined concentric ring bands and determining the number of pixelsof the radial direction of each ring band and reading the output valuecorresponding to information of each ring band in which weighted mean isperformed according to the number of pixels;

iris code generation means for generating the iris code according to theoutput value; and

comparison means for matching the generated iris code with thepreviously registered iris code.

The matching means may match the iris region including a region hiddenby the eyelids.

The iris identification apparatus may further comprise a nonvolatilememory for storing the previously registered iris code, and means forencoding or ciphering the matched result in order to secure security.

The iris identification apparatus may further comprise means foradjusting identification determination level used when matching thegenerated iris code with the previously registered iris code.

According to still another aspect of the present invention, there isprovided an iris identification apparatus for acquiring information ofan iris region of an eye and comparing and matching the acquiredinformation of the iris region with information of an iris regionregistered previously, comprising:

an image pickup sensor having a group of photoelectric conversion pixelsarranged in polar coordinates;

image pickup optical system means for focusing image light from the irisregion on the image pickup sensor;

illumination means for irradiating illumination light to the eye havingthe iris;

optical axis operation control means for matching the center of an irisimage formed on the sensor with the pole of the polar coordinates of thesensor;

light adjustment control means for definitely controlling the innerdiameter of the iris image formed on the sensor by irradiating visiblelight to the eye having the iris from the illumination means andadjusting an amount of the light and defining the pupil diameter;

read scan means for scanning the sensor in the tangential and radialdirections and reading the information of the iris region; and

matching means for matching the information of the iris region read bythe read scan means with the information of the iris region registeredpreviously through pattern matching.

The image pickup optical system means may include a zoom lens anddefinitely keeps the outer diameter of the iris image formed on theimage pickup sensor by the zoom lens.

The matching means may match the iris region including a region hiddenby the eyelids.

The iris identification apparatus may further comprise a nonvolatilememory for storing the previously registered iris code, and means forencoding or ciphering the matched result in order to secure security.

The iris identification apparatus may further comprise means foradjusting identification determination level used when said matchingmeans performs said matching.

According to still another aspect of the present invention, there isprovided an iris identification method for acquiring an iris coderepresenting information of an iris region of an eye and comparing andmatching the acquired iris code with a previously registered iris code,comprising the steps of:

using an image pickup sensor having a group of photoelectric conversionpixels arranged in polar coordinates;

focusing image light from the iris region on the image pickup sensorthrough image pickup optical system means;

matching the center of an iris image formed on the sensor with the poleof the polar coordinates of the sensor through optical axis operationcontrol means;

determining the iris region by acquiring the inner and outer diametersof the iris according to an iris image signal obtained by the sensor;

dividing the determined iris region into predetermined concentric ringbands and determining the number of pixels of the radial direction ofeach ring band and reading the output value corresponding to informationof each ring band in which weighted mean is performed according to thenumber of pixels;

generating the iris code from the output value through iris codegeneration means; and

performing personal identification by matching the generated iris codewith the previously registered iris code.

It is possible to match the iris region including a region hidden by theeyelids.

The previously registered iris code may be stored in a nonvolatilememory, and the iris identification method may further comprise thesteps of encoding or ciphering the matched result in order to securesecurity.

It is possible to make identification determination level whenperforming personal identification adjustable from external orinternally.

According to still another aspect of the present invention, there isprovided an iris identification method for acquiring information of aniris region of an eye and comparing and matching the acquiredinformation of the iris region with information of an iris regionregistered previously, comprising the steps of:

using an image pickup sensor having a group of photoelectric conversionpixels arranged in polar coordinates;

focusing image light from the iris region on the image pickup sensorthrough image pickup optical system means;

irradiating illumination light to the eye having the iris throughillumination means;

matching the center of an iris image formed on the sensor with the poleof the polar coordinates of the sensor through optical axis operationcontrol means;

definitely controlling the inner diameter of the iris image formed onthe sensor by irradiating visible light to the eye having the iris fromthe illumination means and adjusting an amount of the light and definingthe pupil diameter;

scanning the sensor in the tangential and radial directions and readingthe information of the iris region through read scan means; and

performing personal identification by matching the information of theiris region read by the read scan means with the information of the irisregion registered previously through pattern matching.

The image pickup optical system means may include a zoom lens and maydefinitely keep the outer diameter of the iris image formed on the imagepickup sensor by the zoom lens.

It is possible to match the iris region including a region or regionshidden by the eyelids.

It is possible to store the previously registered iris code in anonvolatile memory, and may further comprise the steps of encoding orciphering the matched result in order to secure security.

It is possible to make identification determination level whenperforming personal identification adjustable from external orinternally.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, and advantages, of the present invention willbe more clearly understood from the following detailed description takenin conjunction with the accompanying drawings, in which like referencenumerals designate identical or corresponding parts throughout thefigures, and in which:

FIG. 1 is a block diagram showing the whole construction of an irisrecognition system according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a construction example of an irissensor part of the iris recognition system according to the presentinvention;

FIG. 3 is an illustration showing an example of a sensor;

FIGS. 4A through FIG. 4C are waveform charts showing behavior of anoutput signal level with respect to an angle θ outputted from aband-pass filter 15 and a low-pass filter 22 of FIG. 2;

FIG. 5 is a block diagram showing an alternate construction example ofthe iris sensor part of the iris recognition system according to thepresent invention;

FIG. 6 is an illustration showing a use condition of the iris sensorpart in FIG. 5;

FIG. 7 is a plan view showing a construction example of a sensor;

FIG. 8 is a plan view showing another construction example of thesensor;

FIG. 9 is a plan view showing a further construction example of thesensor;

FIG. 10 is a block diagram showing a further construction example of theiris sensor part;

FIG. 11 is a block diagram showing still a further construction exampleof the iris sensor part;

FIG. 12 is a plan view showing a further construction example of thesensor;

FIG. 13 is a block diagram showing a schematic construction of the irisrecognition system according to another embodiment of the presentinvention;

FIG. 14 is a block diagram showing a schematic construction of the irisrecognition system according to a further embodiment of the presentinvention;

FIG. 15 is an illustration showing the position of the iris; and

FIG. 16 is an illustration showing a schematic construction of a prioriris recognition system.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows the whole construction of an iris recognition system,namely, an iris information acquisition apparatus according to a firstembodiment of the present invention. In FIG. 1, this iris recognitionsystem includes two wide-angle cameras 1 a, 1 b and a zoom camera 7. Thewide-angle cameras 1 a and 1 b take an image of a human eye of a subjectof recognition by CCD's 2 a and 2 b, respectively, and image signalsobtained by the CCD's 2 a and 2 b are fed to an iris acquisitioncontroller 6 after reducing noise of the taken signal with CDS circuits3 a and 3 b. Also, in the wide-angle cameras 1 a and 1 b, CCD drivers 5a and 5 b for driving the CCDs 2 a and 2 b as well as a processingoperation of the CDS circuits 3 a and 3 b are controlled on the basis ofa synchronous control signal generated by control parts 4 a and 4 b.

Also, the system shown in FIG. 1 includes the iris acquisitioncontroller 6 which specifies a three-dimensional position of the humaneye of the subject of recognition according to an image signal inputtedfrom the cameras 1 a and 1 b, and outputs signal or data indicating thespecified result to the zoom camera 7.

The zoom camera 7 drives and controls a steering motor 7 b to move amirror 8 c so that the image pickup direction of the zoom camera 7 isdirected to the human eye according to the three-dimensional positionobtained as mentioned above. Also, the zoom camera 7 controls azoom/focus motor 7 a for driving a zoom lens optical system 8 to befocused on the three-dimensional position of the human eye and regulatesan amount of zoom so that an iris image of the pickup subject coincideswith an image pickup region of a sensor 10. An iris sensor part 9 in thezoom camera 7 feeds position error and focus error information betweenthe iris image taken by the sensor 10 and the sensor to the irisacquisition controller 6.

The iris acquisition controller 6 servocontrols each part of the camerasystem described above until information of the iris part describedabove is obtained. When the information of the iris part is obtained,this information, namely an iris code is matched with a previouslyregistered iris code held within the iris acquisition controller 6 orheld by a host computer (not shown). The matching may be performedeither by the iris acquisition controller 6 or by the host computer.Also, the host computer may control each part of the camera system, orthe sensor part itself may control each part by each error signal of theiris sensor part 9.

Here, the information of the iris part which the iris acquisitioncontroller 6 receives from the iris sensor part 9 is an iris code formedin a binary form by the sensor part 9. A construction of this irissensor part 9 will be described in detail with reference to FIGS. 2 and3.

FIG. 2 shows a detailed construction of the iris sensor part having thesensor 10. This sensor 10 has a pixel array pattern of polar coordinatetype shown in FIG. 3, and each pixel has, for example, a shapepartitioned by straight lines extending in the radial direction (rdirection) and circumferential circles and light receiving areas of eachpixel become larger as the pixel locates at the more outside of theradial direction. The sensor 10 may comprise CCD image sensors or MOStype image sensors. And, the shape of this pixel array pattern is suitedfor each ring shape in the case of acquiring the iris code.

The outer circumferential circle L1 of the pixel array pattern has thesize so as to match with the outer circumference of the iris to be takenor become slightly larger than the outer circumference of the iris, whenfocusing and zooming control are performed, so that necessary resolutionmay be obtained when the iris image is taken.

The inner circumferential circle L2 has the size smaller than the sizewhen the pupil becomes minimum, when the outer circumference of the irismatches with the circle L1. Since the pupil region always exists, thepixel array pattern has a region of a center part E1 surrounded by thecircle L2. In this case, it is necessary to control alignment with thecenter of the iris and that of the pixel array pattern, since the irisimage is taken by the sensor 10 having the pixel array pattern of polarcoordinate type shown in FIG. 3.

A circuit 11 (FIG. 2) for detecting the inner diameter of the irisdetects the boundary between the iris and the pupil of the radialdirection in the taken iris image through the level variation, that is,an edge detection is performed, with the result that the inner diameterof the iris is calculated. On the other hand, a circuit 12 for detectingthe outer diameter of the iris detects the outer circumference of theiris in the taken iris image through the level variation, that is, theedge detection is performed, with the result that the outer diameter iscalculated. Then, the detecting circuits 11 and 12 output a steeringerror signal, namely a signal for indicating a position error of imageformation to the iris acquisition controller 6 according to positions ofthe inner and outer diameters of the iris. Also, the outer diameterdetecting circuit 12 outputs a zoom error signal to the iris acquisitioncontroller 6.

Also, on the assumption that the outer diameter of the iris has matchedwith the outer diameter of the sensor 10 (the outer circumferentialcircle L1), the inner diameter detecting circuit 11 calculates thedifference between the outer diameter of the sensor 10 and the detectedinner diameter to calculate the number of pixels of the radial directionof the sensor 10 corresponding to said difference, and the valueobtained by dividing this number of pixels by the number of ring bands(for example, 8) is fed to a weighted mean processing part 13 as thenumber i of pixels of the radial direction assigned to one ring. Forexample, the number i of pixels is set to “3” in FIG. 3.

Also, the outer diameter of the iris image may not always be matchedwith the outer diameter of the sensor 10. In this case, a zoom opticalsystem is unnecessary and the number i of pixels is calculated on thebasis of the difference between the outer diameter detected by the outerdiameter detecting circuit 12 and the inner diameter detected by theinner diameter detecting circuit 11, but the outer diameter of thesensor 10 must be larger than the outer diameter of the iris image.

The weighted mean processing part 13 calculates a weighted mean of pixeloutput signals of the number i of pixels when receiving the pixel outputsignals from the number i of pixels. The reason why this weighted meanis calculated is because the size of the pixel becomes larger as thepixel of the sensor 10 locates at the more outside as shown in FIG. 3,so that compensation of sensitivity variation caused by the increase inthe light receiving area must be performed, and influence caused by aslight error of the dividing position of each ring and a steering errordue to variation in the pupil diameter is decreased by performing theweighting to the center of each ring.

The value calculated by the weighted mean processing part 13 is fed to ahigh-pass filter 14 as an image output signal. The level or magnitude ofhigh pass component of the image output signal from the high-pass filter14 is taken out and is outputted as a focus control signal.

These steering error signal, zoom error signal and focus control signalare respectively fed to the iris acquisition controller 6. As describedabove, the controller 6 controls the steering motor 7 b and thezoom/focus motor 7 a in the zoom camera 7 so that the iris of the imagepickup subject is matched with the center of the sensor 10 as well asthe outer diameter of the iris is matched with the outer circumferenceof the sensor 10, and the focusing is performed.

A timing generator 20 drives a driver 21 of the sensor 10 and performs ascanning for outputting the pixel signals in the θ direction (rotationaldirection) every ring. When it becomes in the condition capable oftaking a correct image by performing a fine adjustment by a feedbackprocessing mentioned above, the signal outputted from each pixel iscalculated or operated by the weighted mean processing part 13 toperform the weighted mean as described above and is fed to a band-passfilter 15. The band-pass filter extracts the change point in the fedpixel output signal, namely the signal change in the θ direction of theiris pattern. Further, a binary circuit 16 generates an iris code formedin a binary format, by performing conversion of the extracted signalinto binary signal by a built-in comparator. Then, this iris code is fedto the iris acquisition controller 6 through a latch circuit 17.

As described above, the controller 6 compares the iris code of each ringband with the iris code previously registered in the host computer andso on so that a personal identification is performed. Also, the iriscode may preferably be ciphered or encoded in order to secure securityto transmit between each circuit device.

Also, since the upper and lower portions of the iris are hidden byeyelids generally, a circuit 18 for detecting effective range of theouter diameter of the iris detects the boundary between the eyelids andthe iris through the level variation in the radial direction tocalculate the upper and lower limits of the iris to be taken.

A regulating part 19 controls, for example, the timing generator 20 soas to invalidate the range beyond these upper and lower limits. Forexample, in the case of a MOS sensor, addressing in the range beyond thelimits may be skipped.

Also, assuming that the image exists even in the portion hidden by theeyelids, the hide may be ignored. In this case, since a feature patterndoes not exist in the eyelid portion, some degree of correlationdecreases due to the matching of comparison between the eyelids whenidentifying the iris, but it does not matter.

Also, by adding information on the upper and lower limits to, forexample, a header of the iris code, only the effective iris codes or theeffective code portions in the iris code are compared each other whencomparing the iris codes and thus, influence of the eyelids may beremoved. That is, only the effective portions out of the registered iriscodes are used as a comparison subject. Of course, when the iris codesare registered, the eye is preferably opened wide so that the iris isnot hidden by the eyelids as wide as possible.

Further, by adding information on resolution, for example, data forindicating the number of pixels every circumference of the sensor or thenumber of ring bands to the header of the iris code, comparison betweenthe iris codes obtained by the sensors having different resolutions maybe readily performed.

Of course, by adding error-detecting codes such as checksum or CRC codeto, for example, a footer of the iris code, reliability on theregistered iris codes may be improved. Also, the above header and footermay be added to the iris codes registered or the iris codes obtainedfrom the sensor 10, or both the iris codes.

Here, the comparison of the iris codes will be described in furtherdetail. The comparison may be performed as an exclusive OR (EXOR)operation simply, unless a tilt of the eye exists, but the tilt existsgenerally so that the registered iris code is correlated with thedetected iris code and it is determined whether a person having thedetected iris code is the registered person or not, on the basis of thevalue with the highest correlation. This correlation may be performed byselecting the value with the highest correlation out of the valuesobtained when the position at θ=0° of the detected iris code is variedin the range of ±10°, for example.

So-called “hill-climbing” method etc. is used as a method for varyingand obtaining a start point of comparison, and the correlation valuesshifted by one point back and forth are compared each other and theclimbing is performed in the direction of higher correlation. On thecontrary, the iris codes may be compared immediately without acorrelation processing in the case of comparison if the tilt of the θdirection of the eye to be taken can be detected.

Also, the tilt of the eye, namely the tilt of the face may be grasped asa tilt to the horizontal plane formed by straight lines connectingbright points (P1 or P2 etc. in FIG. 15) of illumination reflected inboth eyes to be taken by the wide-angle cameras 1 a and 1 b, correctlythe horizontal plane (at θ=0°) of the zoom camera 7.

Thus, by storing information, in the header of the iris code, on whetherthe iris code is registered with the tilt of the eye compensated or isregistered without the tilt of the eye compensated for example in caseof single eye registration such as a peeping method, it is unnecessaryto perform a useless correlation processing so that the comparison speedmay be improved.

Also, by adding information on which eye is registered to the header, itis unnecessary to decide which eye is registered in the case ofbinocular registration so that the comparison speed may be improved.

Here, output of the band-pass filter 15 may be used, as anotherembodiment of the circuits 11 and 12 for detecting the inner and outerdiameters of the iris, so that the inner and outer diameters of the irismay be detected readily. Also, by adding the low-pass filter 22 andusing output of this filter 22, the steering error signal may beoutputted readily. By performing feedback of this steering error signaldirectly to the steering motor 7 b, steering of the zoom camera 7 may beservocontrolled directly.

That is, when the driver 21 scans the pixel signal of the sensor 10 fromthe inner circumference of the sensor 10 to the outside in the radialdirection, first, the output signal level from the band-pass filter 15is almost zero regardless of an angle θ of the rotation direction asshown in FIG. 4A.

Subsequently, when the pixel signal is scanned in the radial directiongradually, the output signal level indicating detection of the irisportion appears as shown in FIG. 4B, and this output signal is a signaldepending on an iris pattern of the iris portion. Further, when thepixel signal is scanned in the radial direction, the output signal levelis saturated to a certain level and gradually approaches inclinationdetermined by the ratio of light receiving area of each pixel as shownin FIG. 4C.

Therefore, the circuit 11 for detecting the inner diameter of the irisdetects the position on the sensor 10 as the inner diameter of the iris,when the output signal level from the band-pass filter 15 has become acertain level, for example, the output signal level has appeared or hasreached saturation. Similarly, the circuit 12 for detecting the outerdiameter of the iris may detect the outer diameter of the iris throughthe fact that the output signal level from the band-pass filter 15 hasbecome a predetermined level lower from the certain level or has becomea level equal to or lower than a predetermined level. But, in the caseof scanning to the outside in the radial direction, the scanningposition, for example, immediately before the output signal level hasbecome the certain level or lower is detected as the outer diameter ofthe iris.

Of course, the scanning may be performed from the outer circumference ofthe sensor 10 to the inside in the radial direction. Also, it ispossible to calculate the inner diameter of the iris by the scanning tothe outside in the radial direction, and to calculate the outer diameterby the scanning to the inside in the radial direction, so that the innerand outer diameters may be obtained at higher speed in this manner. Byusing the output signal from the band-pass filter 15 thus, the inner andouter diameters of the iris may be detected readily without a compleximage processing.

Further, as shown in FIG. 4C, an envelope L10 of the output signal levelfor the angle θ of the rotational direction may vary with respect to theangle θ of the rotational direction, and level variation in thisenvelope L10 means that the zoom camera 7 is not directed to the eye ofthe image subject. Thus, by providing the low-pass filter 22, the signalof an envelope level of the scanned image signal may be outputted andthe level difference of this signal may be used as the steering errorsignal. In this case, also, the steering error signal may be outputtedby a simple processing without using a complex image processing. Inaddition, the steering may be servocontrolled directly using thissteering error signal.

Also, in FIG. 2, the band-pass filter 15 and the low-pass filter 22receive the signal through the weighted mean processing part 13 andperform a filtering, but a direct pixel signal from the sensor 10 ispreferably used, after filtering, as the signal fed to the inner andouter detecting circuits 11 and 12.

Thus, in the first embodiment, since the sensor 10 is constructed inpixel arrangement having the pixel array pattern of polar coordinatetype shown in FIG. 3, a processing for transforming the orthogonalcoordinate system into the polar coordinate system in the case ofacquiring the image signal by the sensor having the pixel arrangement oforthogonal coordinate type is eliminated so that a processing speed foracquiring the iris code may be improved remarkably.

Also, although the pixel array pattern shown in FIG. 3 has the samedistance between the radii of concentric circles so as to have the samelength of pixel in the radial direction, the length of pixel in theradial direction may be varied according to the rate of stretching andshrinking of the iris. That is, the rate of stretching and shrinking ofthe iris depends on a thickness of the iris, and normally the thicknessof the iris is thinner toward the center of iris and the iris is easy tostretch and shrink, so that the length of pixel of the radial directionin the pixel close to the center may be lengthened according to thisnature of the iris. By varying the length of pixel of the radialdirection thus, rate of recognition may be improved.

Next, a second embodiment will be described with reference to FIG. 5.FIG. 5 shows a construction of an iris sensor part 9 a of an irisrecognition system according to the second embodiment. The iris sensorpart 9 a is different from the iris sensor part 9 shown in FIG. 2 inthat a sensor 10 a is used instead of the sensor 10 and a constructionof the weighted mean processing part 13 is eliminated. The otherconstructions are the same as those of the first embodiment and have thesame reference characters as those of the first embodiment.

The sensor 10 a has pixel arrangement of a pixel array pattern of polarcoordinate type like the sensor 10 and has an illuminating LED 31 (lightemitting diode) which is placed on an optical axis of the sensor andilluminates the eye of human with visible light. Also, it is favorablyconstructed so that the LED 31 may illuminate the eye of human exactlyby shifting the position of a light emitting plane of the LED 31optically from a light receiving plane of the sensor 10 a. Also, an EL(electroluminescence) device etc. other than the LED 31 may be used asillumination means.

On the contrary, the circuit 11 for detecting the inner diameter of theiris detects the inner diameter of the iris, and the difference betweenthis detected inner diameter and the inner circumference of the sensor10 a, namely a pupil diameter error signal is generated and is fed tothe iris acquisition controller 6.

The iris acquisition controller 6 controls brightness of the LED 31 soas to eliminate the pupil diameter error signal. That is, this controlis to increase the brightness of the LED 31 when the pupil diameter islonger than the inner circumference of the sensor 10 a and to decreasethe brightness of the LED 31 when the pupil diameter is shorter than theinner circumference of the sensor 10 a.

By the above control, the pupil diameter always matches with the innercircumference of the sensor 10 a and the outer circumference of thesensor 10 a matches with the outer diameter of the iris through thesteering error signal, the zoom error signal, etc. so that an irisportion of an image subject is taken with the iris portion alwaysmatching with the pixel array pattern on the sensor 10 a.

Thus, the width in the radial direction of each pixel in the sensor maybe determined based on necessary resolving power, so that for example,the length of the sensor in the radial direction may be divided intoeight portions equally, and an iris code may be generated directly usingan image pickup signal from the sensor 10 a.

Also, since division to each ring band is unnecessary and the center ofthe iris is determined, a recognition processing may be performed with avery simple pattern matching by previously registering an iris image.That is, since the inner and outer diameters of the iris are known, thepattern matching may be performed only by rotation at the center of theiris so that a comparison speed may be improved considerably.

Also, In FIG. 5, means for detecting a position error is constructed byproviding an array of photodiodes 32 in the center of the sensor 10 a sothat steering of the zoom camera 7 may be controlled. That is, lightemitted by the LED 31 is reflected on the surface of the eye and isreceived by the photodiodes 32. The steering control is performed byusing the difference between the amounts of light reception in the arrayposition of each photodiode 32 as a steering error signal to feed thedifference to the iris acquisition controller 6.

By using the array of the photodiodes 32 by which the center portion E1is utilized usefully, the difference between the amounts of lightreception may be employed instead of generating the steering errorsignal in the inner detecting circuit 11. Particularly, output of thearray of the photodiodes 32 is fed back to the steering motor 7 bdirectly and analogue servocontrol may be performed so thatminiaturization and weight-saving of the system may be improved.

Further, FIG. 6 shows an example of a position relationship of the eyeto the sensor 10 a etc. in the apparatus of FIG. 5. As shown in FIG. 6,illuminating light 33 emitted from the illuminating LED 31 is irradiatedto the eye through an image pickup lens 8 b. The pupil diameter of theeye is controlled according to the intensity of this irradiated light.The image of the iris having the controlled pupil diameter is formed onthe sensor 10 a through the image pickup lens 8 b. Also, reflected light34 indicates the situation that the reflected light from the LED 31 isirradiated on the photodiodes.

Moreover, the photodiodes 32 described above are preferably arranged inthe proximity of the optical axis of the center of the sensor 10 a andmay also be provided outside the outer circumference of the pixel arraypattern. In this case, the LED 31 may be arranged in the outside of theoptical axis pairing with the photodiodes 32, for example.

Also, in the above-mentioned first embodiment as shown in FIG. 2, alight emitting device for emitting invisible light such as infrared rays(IR) and the photodiodes 32 for receiving reflected light from thislight emitting device may be provided in the same position as the LED 31and so on of the second embodiment. The means for detecting a positionerror is constructed by a combination of such a light emitting deviceand the photodiodes 32, and the steering error signal is obtained sothat positioning of the iris image and the sensor 10 may be performed.

Next, a modification of the second embodiment will be described withreference to FIG. 7. The pixel array pattern of the sensor 10 aconstructing the second embodiment was the pixel array pattern of polarcoordinate type like the sensor 10 and was a set of pixels each having akind of approximately rectangular shape with the pattern divided by thestraight lines of the radial direction every predetermined angle and theconcentric circles every predetermined radius.

On the contrary, in this modification, a sensor 10 b has the pixel arraypattern which is polar coordinate type and is a set of pixels of anapproximately rhombic shape having each diagonal, in the circumferentialdirection and the radial direction as shown in FIG. 7. But, in thispixel array pattern, since a space exists between the pixels due to eachpixel with the rhombic shape, the rhombic pixels are disposed also inthis space so as to effectively utilize the space. Thus, the rhombicpixels on a concentric circle deviates from the rhombic pixels on otherconcentric circle adjacent this in the θ direction by half pixelmutually, and resolution may be improved. Of course, a construction inwhich the pixels are not buried in the space between the pixels may beused. Also, the shape of the pixel is not limited to the rhombic shape.

By using the pixel array pattern having the rhombic pixels with eachdiagonal in the circumferential direction and the radial direction, eachpixel may automatically perform weighting in sensitivity within eachring band in the radial direction, from the shape itself of the lightreceiving part and output the weighted value. The degree of theweighting does not increase the false rejection rate so that the falserejection rate will be suppressed even if there is some steering error,namely the center of the sensor 10 b deviates from the center of theiris image in some degree.

Also, FIG. 8 shows an example of a sensor in which each pixel has anelliptic shape.

Also, FIG. 9 shows a construction of a sensor in which each pixel has aquadrangular or square shape and has the same size. In thisconstruction, the size of each pixel is constant regardless of aposition of the radial direction of the sensor so that the difference insensitivity of each ring band is eliminated.

Next, a third embodiment will be described with reference to FIG. 10.FIG. 10 shows a construction of an iris sensor part 9 b of an irisrecognition system according to the third embodiment. The iris sensorpart 9 b is different from the iris sensor part 9 a shown in FIG. 5 inthat a sensor 10 c which is rotated and driven is used instead of thesensor 10 a. The other constructions are the same as those of the secondembodiment and have the same reference characters.

In FIG. 10, the sensor 10 c is not an area sensor such as the sensors10, 10 a and 10 b but a line sensor or a linear sensor. The sensor 10 csynchronously rotates about the axis corresponding to the center of thesensors 10, 10 a and 10 b by a sensor driving motor 40, and a detectionequivalent to that of the area sensor such as the sensors 10, 10 a and10 b is performed by one rotation. This synchronous rotation is torotate in synchronization with a timing pulse fed from a timinggenerator 20 and so on. Also, when a pixel signal from the sensor 10 cis picked up, the sensor 10 c is rotating so that the pixel signal isoutputted using a rotary transformer or a sliding brush and so on.

The pixels of the sensor 10 c are formed in the rhombic shape having thediagonal in the radial direction like FIG. 7. The reason why thisrhombic shape is adopted is because an operation processing of theweighting is eliminated as described above.

Also, the length of the radial direction of the rhombic pixel asdescribed above may be varied according to the rate of stretching andshrinking of the iris.

Though the third embodiment has some complicated construction incomparison with the first and second embodiments, the sensor 10 c may beconstructed simply and readily in comparison with the sensors 10, 10 aand 10 b.

Also, the construction using the linear sensor may be applied to thefirst embodiment. In this case, each pixel of the linear sensor may nothave the rhombic shape and, for example, may have the rectangular shapeor the other shapes.

Next, a fourth embodiment will be described. In the first embodiment tothe third embodiment, all the image pickup signals are outputted fromthe sensors 10, 10 a to 10 c directly and the edge image is obtainedthrough the band-pass filter 15, and the iris code formed in the binaryformat by the binary circuit 16 is outputted. On the contrary, thefourth embodiment is intended to output the edge image directly by thesensor and the iris code is obtained by converting this outputted signalinto the binary format by the binary circuit 16.

Thus, in the fourth embodiment, the band-pass filter 15 in the firstembodiment to the third embodiment is eliminated, and the constructionof the circuits 11 and 12 for detecting the inner and outer diameters ofthe iris, the high-pass filter 14, and the circuit 18 for detecting theeffective range of the outer diameter of the iris which perform aprocessing on the basis of the edge image is also simplified so that aprocessing load may be reduced.

This construction of the sensor for directly outputting the edge imageis achieved by an optical edge processing using an artificial retinalens disclosed in, for example, Japanese Patent Laid-Open PublicationNo.5-297325. That is, it is constructed so as to receive light inputtedto each pixel in the first embodiment to the third embodiment through aspatial frequency filter and such a construction is an idea of “eye foreye” as it were.

Though a feature extraction of the iris is optically performed in theabove example, this feature extraction may be electrically performed.For example, an outline detecting circuit which is adopted in aneurochip devised by C. A. Mead et al. in California Institute ofTechnology (see C. A. Mead and M. A. Mahowald, “A Silicon Model of EarlyVisual Processing”, Neural Networks, vol.1, pp.91-97 of 1988) andimitates primary sight of the human may be used for this purpose.

FIG. 11 shows a construction example of an iris sensor part using such asensor. The construction shown in FIG. 11 has no construction forconverting an image and extracting an edge image, and in theconstruction, an image edge signal obtained from the sensor is formed ina binary format directly by the binary circuit 16 and an iris code isinputted to a latch 17. Thus, no band-pass filter 15 shown in theconstruction of FIG. 5 is required.

Also, although all the sensors have the pixel array pattern of polarcoordinate type in each embodiment described above, the sensor is notlimited to this pattern and, for example, as shown in FIG. 12, thesensor may have a pattern in which pixels PP are arranged in a spiralshape from the inner diameter of the iris of the sensor.

In the case of the sensor having this spiral array pattern, since thesensor functions as an one-dimensional sensor, a processing may beperformed so as not to be affected by the variation in the pupildiameter, for example, by assigning serial numbers to each pixel fromthe outer circumference and detecting that the pixels from No.1 to No.Nare the iris portion and normalizing said pixels with N. In this case,particularly, read control of each pixel is simplified. Also, even forthe sensor of polar coordinate type, an one-dimensional read scan may beimplemented by joining the pixels of each concentric circle in the samemanner of the spiral sensor.

Further, in the case of taking the iris image as a color sensor in whichthe pixels are arranged in the spiral shape with three R, G, B,addressing of each pixel forming the iris portion is facilitated.

The construction capable of obtaining the iris code from the sensor partfor the iris recognition system has been described hereinbefore. On thecontrary, by incorporating a comparison circuit for comparing thedetected iris code with a predetermined code into a sensor chip itselfand incorporating a nonvolatile memory capable of registering the iriscodes for comparison to some degree simultaneously, it may beconstructed so as to output not the iris code but the comparison result,namely the identification result (for example, OK or NG) from the sensorpart. In this case, this output is preferably ciphered or encoded tofeed in order to secure security. By such a construction, a smallidentification apparatus used instead of keys of house, room, car, etc.may be implemented by only this chip, with the result that range ofapplication may be extended.

Also, since it is supposed that iris detection of facing type may beused, the construction may be simplified using relative paralleltranslation of a VAP (vertical angle variable prism) or a plurality oflenses instead of preprocessing such as alignment of the iris by thewide-angle cameras mentioned above. For example, in the case of usingthe VAP as shown in FIG. 13, the iris image may be obtained by controlof only an optical system including the vertical angle variable prism 8a and a zoom lens 8 b and a zoom camera including an iris sensor part 9c.

Also, in FIG. 13, the numeral 7 c designates a pan/tilt motor fordriving the prism 8 a and the numeral 7 d designates a zoom/focus motor.Also, the numeral 6a designates an iris acquisition controller and acontrol part of the wide-angle cameras as the iris acquisitioncontroller 6 shown in FIG. 1 is not required so that the controller 6 ais simplified.

Further, FIG. 14 shows a construction in which a controller 50 fordriving and controlling the VAP 8 a and the zoom lens 8 b, a memory 51for storing the iris code for comparison, a comparison circuit 52 forcomparing the detected iris code with the iris code stored in thememory, and a cipher circuit 53 are integrated into one chip. By such aconstruction, the cost necessary for the iris recognition system may bereduced more. Any memory device such as a hard disk unit, amagnet-optical disk unit other than the nonvolatile semiconductor memorymay be used as the memory 51.

Also, it is possible to make identification determining level, that is,threshold of correlation degree of iris codes, adjustable. For example,in FIG. 14, a determination value register 54 is provided. Adetermination value indicating an identification determining level canbe stored in the determination value register 54, for example, fromexternal, to designate a required correlation level. Also, it ispossible to selectively supply one of a plurality of determinationvalues from external to the determination value register 54.

It is also possible to provide a plurality of determination valueregisters and a selecting circuit for selecting one of the outputs ofthe registers.

It is further possible to make the identification determination leveladjustable internally, for example, based on the determination valuesupplied from a microprocessor in the iris recognition system. Themicroprocessor may generate the determination value, for example,depending on various conditions, such as brightness of the location theiris recognition system is installed, required precision of recognition,and the like.

In the above embodiment of facing type, it may be constructed so that athree-dimensional alignment processing, which has been performed by thewide-angle cameras 1 a and 1 b, to the zoom lens 8 b is performed byapproach of the subject to a predetermined distance and position fromthe apparatus, and only fine adjustment to perform positioning andfocusing so as to direct the optical axis of the zoom lens 8 b preciselytoward the position of the eye using the known VAP 8 a is controlled bythe iris acquisition controller or the sensor part itself.

The margin of range of such a predetermined position is about ±3 cm in adistance of 25 to 30 cm from the apparatus, so-called, a distance ofdistinct vision. Further, in the case of providing an illuminating LEDon the optical axis of the sensor, the pupil diameter may be adjustedsimultaneously if the subject is asked to look this LED.

Also, it is obvious that a method in which a person peeps into the zoomlens 8 b from a given window etc. may be adopted without a method forfacing at the distance of distinct vision. The difference between thefacing method and the peeping method is that a focal length of the imagepickup lens 8 b only differs. Also, the lens 8 b may not always be azoom lens and may be a lens with single focal point or a lens capable ofswitching the focal length.

Particularly, when a screen of a personal computer may be used in thepersonal recognition of electronic business, focusing may be performedeven using a camera with a fixed focal point etc. by displaying an irisimage and a cross line on the screen to perform steering, and displayinga message of “please approach the screen a little”, for example.

In this case, practically, the iris image is obtained by attaching anadapter lens to a normal camera mounted in the personal computer as anattachment or an option other than a method for attaching a dedicatedcamera to the iris recognition system, and coordinate transformation isperformed by a software of the personal computer and the iris code maybe obtained. Also, the iris code may be obtained by connecting adedicated sensor and a normal CCD/MOS sensor to the iris recognitionsystem through a half mirror and mounting both the sensors.

Also, it is possible to construct a band-pass filter using a normal LCRand compare output of the band-pass filter with a predeterminedthreshold value by a comparator to form in a binary format. On thecontrary, a function equivalent to the construction including theband-pass filter and the comparator may be achieved by calculating theaverage of outputs of continuous N pixels and comparing this averagewith output of a target pixel. In this case, a comparison processing maybe executed without being affected by a scan speed, and also, abandwidth of the band-pass filter may be varied by selecting the valueof N, so that more flexible processing may be performed. Also, thecontinuous N pixels may be selected from the range including the pixelsto be compared or from backward and forward of the range including thepixels to be compared.

In the above description, the method has been mainly described in whichfeatures of the tangential direction of the iris are extracted byscanning in the tangential direction of the sensor. However, in thepresent invention, it is preferable that scanning is also performed inthe radial direction to extract features of its direction. But, sincegenerally a spatial frequency of the radial direction is not too highjudging from the feature of the iris pattern, resolving power is reducedby taking a weighted mean of the tangential direction according to this(for example, 32 division) and the scanning in the radial direction isperformed, so that redundancy may be reduced favorably.

Further, in this case, it is unnecessary to increase the resolving power(for example, 16 division) of the radial direction too. Anyway, acircuit construction like the circuit construction used for scanning inthe tangential direction may be used to perform the scanning in theradial direction. Particularly, in the case of constructing theband-pass filter by the comparison with the average of the N pixels, itmay also be used as the band-pass filter in the radial direction.

It is also possible to perform scanning only in the tangentialdirection. Also, it is possible to perform scanning in the tangentialdirection in a ring band and check if sufficient iris information isobtained to perform identification. If sufficient iris information hasnot yet been obtained, it is possible to scan in the tangentialdirection of the next ring band.

The above-mentioned embodiments or the modifications may be combinedrespectively if desired. Further, the present invention may be appliedto the eye of human as well as animals generally and, for example,individual identification thereof may be performed.

As described in detail above, since the present invention uses an imagepickup sensor comprising a group of pixels arranged in polarcoordinates, it is unnecessary to transform an orthogonal coordinatesystem into a polar coordinate system in order to obtain an iris code,and the iris code may be generated at high speed without a dedicatedprocessor, so that time necessary for personal identification may besaved and a load of a processing apparatus may be reduced.

Also, since no apparatus for performing coordinate transformation isrequired, miniaturization and weight-saving of a system may be improved.

Also, since an image of an iris portion with the same size always may beacquired by using means for regulating light, an information processingof the iris portion is facilitated and particularly, a check processingusing a pattern matching may also be performed.

Also, when a device for detecting edge information electrically oroptically is used as the image pickup sensor, a load necessary forgeneration processing of the iris code is reduced and the processing maybe performed at high speed and further, miniaturization andweight-saving of the system may be promoted.

Further, by forming the pixels of the image pickup sensor inapproximately rhombic shape, it is unnecessary to perform compensationof sensitivity and weighting, with the result that the load necessaryfor generation processing of the iris code may be reduced and the timemay be saved.

Still further, since pixel density of the radial direction is variedaccording to rate of stretching and shrinking of the iris, the decreasein recognition rate accompanying the stretching and shrinking of theiris may be prevented.

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the present invention as set forthin the claims below. Accordingly, the specification and figures are tobe regarded in an illustrative sense rather than a restrictive sense,and all such modifications are to be included within the scope of thepresent invention. Therefore, it is intended that this inventionencompasses all of the variations and modifications as fall within thescope of the appended claims.

What is claimed is:
 1. An iris information sensor comprising: an imagepickup sensor having a group of photoelectric conversion pixels arrangedin polar coordinates; a focuser that focuses image light from an irisregion of an eye on the image pickup sensor so that the center of aniris image formed on the sensor substantially matches with the pole ofthe polar coordinates of the sensor; and a scanner that sequentiallyscans the photoelectric conversion pixels of the sensor to read out aniris image signal.
 2. The iris information acquisition apparatus asdefined in claim 1, wherein the image pickup sensor comprises a group ofpixels arranged in concentric circles.
 3. The iris informationacquisition apparatus as defined in claim 1, wherein the image pickupsensor comprises a group of pixels arranged in a spiral shape extendingin the radial direction.
 4. An iris information acquisition apparatusfor obtaining image information of an iris region, comprising: an imagepickup sensor having a group of photoelectric conversion pixels arrangedin polar coordinates; an image pickup optical focuser that focuses imagelight from the iris region on the image pickup sensor; an optical axisoperation controller that substantially matches the center of an irisimage formed on the sensor with the pole of the polar coordinates of thesensor; a region determiner that determines the iris region by acquiringthe inner and outer diameters of the iris according to an iris imagesignal obtained by the sensor; and a read scanner that scans thedetermined iris region in a predetermined sequence and obtains an outputvalue corresponding to information of the iris region.
 5. The irisinformation acquisition apparatus as defined in claim 4, wherein saidread scanner scans the determined iris region at least in the tangentialdirection.
 6. The iris information acquisition apparatus as defined inclaim 4, wherein said read scanner that scans the determined irisregion, scans the determined iris region in the tangential and radialdirections at predetermined intervals.
 7. The iris informationacquisition apparatus as defined in claim 4, wherein said read scannerdivides the determined iris region into predetermined concentric ringbands, determines the number of pixels in the radial direction of eachring band and reads the output value corresponding to information ofeach ring band in which a weighted mean is performed according to thenumber of pixels.
 8. The iris information acquisition apparatus asdefined in claim 4, wherein said region determiner determines the irisregion according to an amplitude of a feature extraction signal, saidfeature extraction signal obtained by passing the image signal through aband-pass filter, said image signal obtained by scanning the imagepickup sensor in the tangential direction.
 9. The iris informationacquisition apparatus as defined in claim 4, wherein said regiondeterminer determines the iris region according to level variation inthe image signal obtained by the scan in the radial direction of theimage pickup sensor.
 10. The iris information acquisition apparatus asdefined in claim 4, wherein said optical axis operation controllercalculates the direction and size of an error between the center of theiris image formed on the image pickup sensor and the pole of the polarcoordinates of the sensor to control a matching of the center of theiris image with the pole of the polar coordinates of the sensor, byfurther passing the feature extraction signal through a low-pass filter,said feature extraction signal obtained by passing the image signalthrough the band-pass filter, said image signal obtained by scanning theimage pickup sensor in the tangential direction.
 11. The irisinformation acquisition apparatus as defined in claim 4, furthercomprising an illuminator that irradiates illumination light to the eyeand a group of light receiving elements that receive reflectedillumination light from the eye, said optical axis operation controllercontrolling a matching of the center of the iris image with the pole ofthe polar coordinates of the image pickup sensor according to an amountof receiving light of the group of light receiving elements.
 12. Theiris information acquisition apparatus as defined in claim 4, furthercomprising an iris code generator that generates an iris code accordingto the output value read by the read scanner.
 13. The iris informationacquisition apparatus as defined in claim 4, wherein said optical axisoperation controller controls a matching of the center of the iris imageformed on the image pickup sensor by moving a mirror placed in anoptical path between the iris of the eye of a subject and the sensorwith the pole of the polar coordinates of the sensor.
 14. The irisinformation acquisition apparatus as defined in claim 4, wherein saidoptical axis operation controller controls a matching of the center ofthe iris image formed on the image pickup sensor by moving the sensorwith the pole of the polar coordinates of the sensor.
 15. The irisinformation acquisition apparatus as defined in claim 4, wherein saidoptical axis operation controller controls a matching of the center ofthe iris image formed on the image pickup sensor by a vertical anglevariable prism placed in an optical path between the iris of the eye ofa subject and the sensor with the pole of the polar coordinates of thesensor.
 16. The iris information acquisition apparatus as defined inclaim 4, wherein said optical axis operation controller controls amatching of the center of the iris image formed on the image pickupsensor by mutually translating a plurality of lenses placed in anoptical path between the iris of the eye of a subject and the sensorwith the pole of the polar coordinates of the sensor.
 17. The irisinformation acquisition apparatus as defined in claim 4, wherein saidimage pickup sensor comprises a linear sensor in which pixels arearranged in the radial direction and a rotation driver thatsynchronously rotates the linear sensor around the pole of the polarcoordinates, and a function equivalent to the group of the pixels of thepolar coordinates is achieved by the rotation of the linear sensorthrough the rotation driver.
 18. The iris information acquisitionapparatus as defined in claim 4, wherein each pixel of the image pickupsensor comprises one of a MOS sensor and a CCD sensor.
 19. The irisinformation acquisition apparatus as defined in claim 4, wherein eachpixel of the image pickup sensor comprises a detector that detects edgeinformation one of electrically and optically.
 20. The iris informationacquisition apparatus as defined in claim 4, wherein pixel density inthe radial direction of each pixel of the image pickup sensorcorresponds to the rate of stretching and shrinking of the iris.
 21. Theiris information acquisition apparatus as defined in claim 4, whereinthe image pickup sensor comprises a group of pixels arranged in a spiralshape extending in the radial direction.
 22. An iris informationacquisition apparatus for obtaining image information of an iris regionof the eye, comprising: an image pickup sensor comprising a group ofphotoelectric conversion pixels arranged in polar coordinates; an imagepickup optical focuser that focuses image light from the iris region onthe image pickup sensor; an illuminator that irradiates illuminationlight to the eye having the iris; an optical axis operation controllerthat substantially matches the center of an iris image formed on thesensor with the pole of the polar coordinates of the sensor; a lightadjustment controller that controls the inner diameter of the iris imageformed on the sensor by irradiating visible light to the eye having theiris from the illuminator, adjusting an amount of the light and definingthe pupil diameter; and a read scanner that scans the sensor in apredetermined sequence and reads image information of the iris region.23. The iris information acquisition apparatus as defined in claim 22,wherein said read scanner scans the determined iris region at least inthe tangential direction.
 24. The iris information acquisition apparatusas defined in claim 22, wherein said read scanner scans the determinediris region in the tangential and radial directions at predeterminedintervals.
 25. The iris information acquisition apparatus as defined inclaim 22, wherein said image pickup optical focuser comprises a zoomlens, the zoom lens ensuring that the outer diameter of the iris imageis formed on the image pickup sensor.
 26. The iris informationacquisition apparatus as defined in claim 22, wherein each pixel of theimage pickup sensor has a light receiving region with an approximatelyrhombic shape having each diagonal in the radial and tangentialdirections of the polar coordinates.
 27. The iris informationacquisition apparatus as defined in claim 22, wherein each pixel of theimage pickup sensor is also arranged in a region with an approximatelyrhombic shape surrounded by the light receiving regions with theapproximately rhombic shape.
 28. The iris information acquisitionapparatus as defined in claim 22, further comprising an iris codegenerator that generates an iris code according to the output value readby the read scanner.
 29. The iris information acquisition apparatus asdefined in claim 28, wherein said iris code generator comprises acomparitor that compares a band-pass filter receiving the output valueand output of the band-pass filter with a predetermined threshold value.30. The iris information acquisition apparatus as defined in claim 28,wherein said iris code generator generates the iris code by comparingthe output value of a plurality of continuous pixels with output of atarget pixel.
 31. The iris information acquisition apparatus as definedin claim 28, wherein information on the effective range of the irisregion is added to the iris code.
 32. The iris information acquisitionapparatus as defined in claim 28, wherein information on resolution ofthe image pickup sensor is added to the iris code.
 33. The irisinformation acquisition apparatus as defined in claim 28, whereininformation on tilt of the eye is added to the iris code.
 34. The irisinformation acquisition apparatus as defined in claim 28, whereininformation on whether the iris code is the right eye or the left eye isadded to the iris code.
 35. The iris information acquisition apparatusas defined in claim 22, further comprising a group of light receivingelements that receive reflected light from the eye by said illuminator,said optical axis operation controller controls a matching of the centerof the iris image with the pole of the polar coordinates of the imagepickup sensor according to an amount of receiving light of the group oflight receiving elements.
 36. The iris information acquisition apparatusas defined in claim 22, wherein said optical axis operation controllercalculates the direction and size of an error between the center of theiris image formed on the image pickup sensor and the pole of the polarcoordinates of the sensor to control a matching of the center of theiris image with the pole of the polar coordinates of the sensor, byfurther passing a feature extraction signal through a low-pass filter,said feature extraction signal obtained by passing the image signalthrough the band-pass filter, said image signal obtained by scanning theimage pickup sensor in the tangential direction.
 37. The irisinformation acquisition apparatus as defined in claim 22, wherein saidoptical axis operation controller controls a matching of the center ofthe iris image formed on the image pickup sensor by moving a mirrorplaced in an optical path between the iris of the eye of a subject andthe sensor with the pole of the polar coordinates of the sensor.
 38. Theiris information acquisition apparatus as defined in claim 22, whereinsaid optical axis operation controller controls a matching of the centerof the iris image formed on the image pickup sensor by-moving the sensorwith the pole of the polar coordinates of the sensor.
 39. The irisinformation acquisition apparatus as defined in claim 22, wherein saidoptical axis operation controller controls a matching of the center ofthe iris image formed on the image pickup sensor by a vertical anglevariable prism placed in an optical path between the iris of the eye ofa subject and the sensor with the pole of the polar coordinates of thesensor.
 40. The iris information acquisition apparatus as defined inclaim 22, wherein said optical axis operation controller controls amatching of the center of the iris image formed on the image pickupsensor by mutually translating a plurality of lenses placed in anoptical path between the iris of the eye of a subject and the sensorwith the pole of the polar coordinates of the sensor.
 41. The irisinformation acquisition apparatus as defined in claim 22, wherein saidimage pickup sensor comprises a linear sensor in which pixels arearranged in the radial direction and a rotation driver thatsynchronously rotates the linear sensor around the pole of the polarcoordinates, and a function equivalent to the group of the pixels of thepolar coordinates is achieved by the rotation of the linear sensorthrough the rotation driver.
 42. An iris information acquisitionapparatus as defined in claim 22, wherein each pixel of the image pickupsensor comprises one of a MOS sensor and a CCD sensor.
 43. The irisinformation acquisition apparatus as defined in claim 22, wherein eachpixel constructing the image pickup sensor comprises a detector thatdetects edge information one of electrically and optically.
 44. The irisinformation acquisition apparatus as defined in claim 22, wherein pixeldensity in the radial direction of each pixel of the image pickup sensorcorresponds to the rate of stretching and shrinking of the iris.
 45. Theiris information acquisition apparatus as defined in claim 22, whereinthe image pickup sensor comprises a group of pixels arranged in a spiralshape extending in the radial direction.
 46. An iris identificationapparatus for acquiring an iris code representing information of an irisregion of the eye and comparing and matching the acquired iris code witha previously registered iris code, comprising: an image pickup sensorcomprising a group of photoelectric conversion pixels arranged in polarcoordinates; an image pickup optical focuser that focuses image lightfrom the iris region on the image pickup sensor; an optical axisoperation controller that substantially matches the center of an irisimage formed on the sensor with the pole of the polar coordinates of thesensor; a region determiner that determines the iris region by acquiringthe inner and outer diameters of the iris according to an iris imagesignal obtained by the sensor; a read scanner that divides thedetermined iris region into predetermined concentric ring bands anddetermines the number of pixels in the radial direction of each ringband and reads the output value corresponding to information of eachring band in which weighted mean is performed according to the number ofpixels; an iris code generator that generates the iris code according tothe output value; and a comparitor that matches the generated iris codewith the previously registered iris code.
 47. The iris identificationapparatus as defined in claim 46, wherein said comparitor that matchesthe iris region including a region hidden by the eyelids.
 48. The irisidentification apparatus as defined in claim 46, further comprising anonvolatile memory that stores the previously registered iris code, andone of an encoder that encodes and a cipher that ciphers the matchedresult in order to provide security.
 49. The iris identificationapparatus as defined in claim 48, further comprising an adjuster thatadjusts the identification determination level used when matching thegenerated iris code with the previously registered iris code.
 50. Aniris identification apparatus that acquires information of an irisregion of the eye and compares and matches the acquired information ofthe iris region with information of an iris region registeredpreviously, comprising: an image pickup sensor comprising a group ofphotoelectric conversion pixels arranged in polar coordinates; an imagepickup optical focuser that focuses image light from the iris region onthe image pickup sensor; an illuminator that radiates illumination lightto the eye having the iris; an optical axis operation controller thatsubstantially matches the center of an iris image formed on the sensorwith the pole of the polar coordinates of the sensor; a light adjustmentcontroller that controls the inner diameter of the iris image formed onthe sensor by irradiating visible light to the eye having the iris fromthe illuminator, adjust an amount of the light and defines the pupildiameter; a read scanner that scans the sensor in the tangential andradial directions and reads the information of the iris region; and amatcher that matches the information of the iris region read by the readscanner with the information of the iris region registered previouslythrough pattern matching.
 51. The iris identification apparatus asdefined in claim 50, wherein said image pickup optical focuser includesa zoom lens, the zoom lens ensuring that the outer diameter of the irisimage is formed on the image pickup sensor.
 52. The iris identificationapparatus as defined in claim 50, wherein the matcher matches the irisregion including a region hidden by the eyelids.
 53. The irisidentification apparatus as defined in claim 50, further comprising anonvolatile memory that stores the previously registered iris code, andone of an encoder that encodes and a cipher that ciphers the matchedresult in order to provide security.
 54. The iris identificationapparatus as defined in claim 53, further comprising an adjuster thatadjusts an identification determination level used when said matcherperforms said matching.
 55. An iris identification method for acquiringan iris code representing information of an iris region of the eye andcomparing and matching the acquired iris code with a previouslyregistered iris code, comprising: using an image pickup sensorcomprising a group of photoelectric conversion pixels arranged in polarcoordinates; focusing image light from the iris region on the imagepickup sensor through an image pickup optical system; substantiallymatching the center of an iris image formed on the sensor with the poleof the polar coordinates of the sensor through an optical axis operationcontroller; determining the iris region by acquiring the inner and outerdiameters of the iris according to an iris image signal obtained by thesensor; dividing the determined iris region into predeterminedconcentric ring bands, determining the number of pixels in the radialdirection of each ring band and reading the output value, correspondingto information of each ring band in which a weighted mean is calculatedaccording to the number of pixels; generating the iris code from theoutput value through an iris code generator; and performing personalidentification by matching the generated iris code with the previouslyregistered iris code.
 56. The iris identification method as defined inclaim 55, wherein the iris region, including a region hidden by theeyelids, is matched.
 57. The iris identification method as defined inclaim 55, wherein the previously registered iris code is stored in anonvolatile memory, and further comprising one of encoding and cipheringthe matched result in order to provide security.
 58. The irisidentification method as defined in claim 57, wherein an identificationdetermination level, when performing personal identification, isadjustable.
 59. An iris identification method for acquiring informationof an iris region of the eye and comparing and matching the acquiredinformation of the iris region with information of an iris regionregistered previously, comprising: using an image pickup sensorcomprising a group of photoelectric conversion pixels arranged in polarcoordinates; focusing image light from the iris region on the imagepickup sensor through an image pickup optical system; irradiatingillumination light to the eye having the iris through an illuminator;substantially matching the center of an iris image formed on the sensorwith the pole of the polar coordinates of the sensor through an opticalaxis operation controller; controlling the inner diameter of the irisimage formed on the sensor by irradiating visible light to the eyehaving the iris from the illuminator, adjusting an amount of the lightand defining the pupil diameter; scanning the sensor in the tangentialand radial directions and reading the information of the iris regionthrough a read scanner; and performing personal identification bymatching the information of the iris region read by the read scannerwith the information of the iris region registered previously throughpattern matching.
 60. The iris identification method as defined in claim59, wherein said image pickup optical system includes a zoom lens, thezoom lens ensuring that the outer diameter of the iris image is formedon the image pickup sensor.
 61. The iris identification method asdefined in claim 59, wherein the iris region, including a region, hiddenby the eyelids, is matched.
 62. The iris identification method asdefined in claim 59, wherein the previously registered iris code isstored in a nonvolatile memory, and further comprising one of encodingand ciphering the matched result in order to provide security.
 63. Theiris identification method as defined in claim 62, wherein anidentification determination level, when performing personalidentification, is adjustable.
 64. An iris information sensing methodusing an iris image pickup sensor having a group of photoelectricconversion pixels arranged in polar coordinates, the method comprising:focusing image light from an iris of an eye on the image pickup sensorso that the center of an iris image formed on the sensor substantiallymatches with the pole of the polar coordinates of the sensor; andsequentially scanning the photoelectric conversion pixels of the sensorto read out an iris image signal.